In the past, in the field of gas turbines, there has been a gas turbine that uses a premixed combustion type combustor as a combustor that blows fuel into compressed air, thereby performing combustion. As the premixed combustion type combustor, there is a combustor that includes a combustor basket to which compressed air is supplied from a compressor, a plurality of main nozzles annularly disposed along the inner periphery of the combustor basket, and a pilot nozzle that is disposed on the center axis of the combustor basket and that holds a pilot flame. This type of combustor performs premixed combustion by supplying premixed gas of fuel and compressed air to the inside of the combustor basket by the main nozzles and igniting the premixed gas using the pilot flame.
For example, in Patent Document 1 below, a premixed combustion burner is constituted of a fuel nozzle, a burner cylinder that surrounds the fuel nozzle so as to form an air pathway between the burner cylinder and the fuel nozzle, and a swirler that is disposed at plural places in the circumferential direction of the outer peripheral surface of the fuel nozzle and which swirls air flowing therethrough. In this combustor, a vortical air flow is generated on the downstream of the swirler by forming a cutout portion in a trailing edge portion on the inner periphery of the swirler, and thus the fuel concentration of the premixed gas is made uniform in the radial direction of the air pathway, whereby suppression of an increase in NOx and prevention of reversion (flashback) of a flame are attempted.